The invention relates to a method and a device for forming a scaled flow of overlapped flat articles, which are supplied and removed with their longitudinal sides positioned between side mounted guide means.
The overlapping of articles is advantageous, for example, for the space-saving transport of the articles in sorting machines or the secure stacking in stacking compartments where a following article is to be prevented from bumping into the rear edge of a preceding article.
A solution has become known (DE 37 23 259 C2), which provides in addition to the main conveying track a secondary conveying track with diverters to prevent a backing up of the articles during the stacking in. This arrangement calls for the overlapping of two successive articles.
Two variants are possible here:
1. A second article takes a shorter path as compared to a first article, as a result of which a varied degree of overlapping can be achieved when the articles converge, depending on the length of the article and the gap. PA0 2. A second article is transported at a higher speed, relative to a first article. If the speed can be controlled, then a constant overlapping can be achieved when the articles converge.
However, a continuous scaled flow cannot be produced with this. An additional disadvantage is the relatively high expenditure. In the operational sequence sorter SLS for letters, manufactured by the company Elsag Bailey, Genoa, a continuous or a discontinuous flow of individual articles is taken over by a second conveying system. This system operates in the start-stop mode with constant intervals. In the course of this, the following article is deposited on the preceding article in such a way that the front edge of the articles is always stopped in the same position and subsequently, the resulting scale is moved forward by a constant distance. The resulting scaled flow thus has a constant spacing between the front edges of the articles.
In order to prevent bumping against the rear edges of the preceding articles during the overlapping, the articles must arrive at the second conveying system at a pointed angle, wherein the rear edges of the articles must leave the resulting entry triangle in a timely fashion.
Owing to the fact that articles with a varying format are to be processed, a correspondingly large gap must exist, oriented toward the long articles with their large, empty surfaces since the rear edges of the long articles leave the entry triangle only relatively slowly as a result of their inherent mass inertia and stiffness, thereby resulting in a low flow rate, or a correspondingly involved auxiliary device must be used to ensure that the rear edges clear the entry triangle quickly, e.g. a stacking spindle (DE-OS 33 17 865) or a contact pressure roller (DE-OS 37 00 827).